1270 - Smeech
Time Limit : 1 Second
Memory Limit : 128 MB
Submission: 134
Solved: 26
- Description
- Professor Octastichs has invented a new programming language, Smeech. An expression in Smeech may be a positive or negative integer, or may be of the form (p e1 e2) where p is a real number between 0 and 1 (inclusive) and e1 and e2 are Smeech expressions. The value represented by a Smeech expression is as follows: An integer represents itself With probability p, (p e1 e2) represents x + y where x is the value of e1 and y is the value of e2; otherwise it represents x - y. Given a Smeech expression, what is its expected value?
- Input
- Input consists of several Smeech expressions, one per line, followed by a line containing ().
- Output
- For each expression, output its expected value to two decimal places.
- sample input
-
7 (.5 3 9) ()
- sample output
-
7.00 3.00
- hint
- source
- waterloo 29 September, 2007